A typical approach to manufacturing beverage or other containers (such as, commonly, 12 ounce to 32 ounce pop or beer containers), involves a two piece construction procedure involving forming a body piece which contains a (typically cylindrical) sidewall and a bottom, all formed from a single piece of metal, typically aluminum, and a second top or cover piece joined to the neck of the body piece, e.g. by a double seaming or curling operation. An important consideration in designing and fabricating such containers involves providing a desirable balance between minimizing material requirements (such as providing relatively thin-gauge metal) while achieving a container that will maintain its integrity and/or form, despite shipping and handling impacts or forces and impact arising from dropped containers and shipping mishaps. Moreover, it is critical to provide containers which maintain integrity and/or form even when contents are under pressure due to carbonated or otherwise gas-pressured contents and/or arising from high internal temperatures, including, in some cases, pasteurization temperatures.
Typical beverage container forming processes include subjecting a thin sheet of metal alloy to a series of drawing, ironing, and/or forming operations. One of the first steps performed on such a metal sheet is a cupping process where the sheet is drawn into a seamless cup to establish an initial shape and inside diameter of the container. Subsequently, the cup is pushed through a series of ironing rings to thin the outer wall of the container to a selected thickness. During these ironing processes, performed with equipment commonly referred to as bodymaker tooling, the diameter of the container is typically maintained while the outer wall length is substantially increased to establish the fluid capacity of the container. The bottom portion of the container is generally formed to define a recessed or concave dome surface to resist deformation due to internal fluid pressures. The pressure at which the recessed surface is deformed or reversed is often called the “static dome reversal pressure” of the container. The bottom portion of the container also includes an annular support member which will contact a supporting surface to maintain the container in a vertical position during stacking, consumer use, and the like.
As mentioned above, reduction in raw material required to manufacture such a container is highly desirable. One successful method known in the art for reducing raw material usage has been to reduce the diameter of the top and bottom portions of the can, commonly known as “necking.” By reducing the diameter of the top and bottom portions of the can, the material usage for the “lid” portion of the can is significantly reduced, and even a small reduction in this diameter can result in significant cost reductions for a container manufacturing operation. Two container diameter sizes for soda and beer containers are 2 {fraction (2/16)} inches and 2{fraction (4/16)} inches, which are commonly known as 202 and 204 containers, respectively. Numerous other diameter sizes exist, and are well known in the art. Many manufacturers produce 202 and 204 containers using the same bodymaker tooling, and perform different operations to obtain the appropriate sized end closure or “lid” portions.
Specifically, for the annular support member on the bottom portion, an additional step known as reprofiling is performed on a container which has a nominal 204 diameter to obtain a 202 sized container. The annular support member generally contains outer and inner surfaces that join the outer wall to the annular support member and that join the annular support member to the domed surface, respectively. These outer and inner surfaces have profiles which are shaped during the manufacture of the container, to provide an outside dome profile, and an inside dome profile. The configuration of the bottom portion is important in facilitating material usage reductions, since various geometric configurations can be utilized to enhance strength characteristics. For example, the bottom portion may be configured to enhance the static dome reversal pressure characteristics and to reduce the risk of damage caused when a filled container is dropped onto a hard surface during shipping storage and use. This drop resistance may be described as the cumulative drop height at which the bottom portion is damaged sufficiently to preclude the container from standing upright on a flat surface, or stacking on another container.
A process known as “reforming” has been widely used, in which the inside dome profile of the bottom portion of a container is formed to create a geometric configuration with improved strength characteristics. Reforming results in increased buckle and drop strength for beverage containers. The outside dome profile is also often configured, i.e., reprofiled for purposes of enhancing of the stacking capability of beverage containers and to improve the strength. Further, reform/reprofiling has also been proven to control “dome growth”, a condition where a container gets taller after going through the pasteurizing process. As mentioned above, in order to have a manufacturing plant which is able to manufacture both 204 and 202 cans, the bottom portion of the can may be reprofiled which reworks the outside dome profile to a reduced diameter 202 beverage container from a 204 beverage container.
Typical can manufacturing facilities, as mentioned above, contain expensive capital equipment and often produce hundreds of millions of beverage containers per year. Accordingly, it is beneficial to have a facility which is able to produce both 202 and 204 beverage cans, in order to provide customers with both type of cans without requiring a separate manufacturing facility. Both 202 and 204 beverage cans can be produced with the same bodymaker tooling, resulting in the factory only requiring the selection of the post process reprofiling, or none, to achieve either a 202 or a 204 dome at the end of the process line.
Currently, when a factory wants to combine the two processes to produce a 202 beverage can with improved dome properties, it requires the use of two machines in tandem. First, a reforming tool is used to form the appropriate inside dome geometric profile required for various dome strength parameters as mentioned above. Following the reforming operation is a reprofiling operation, in which a reprofiling tool is used to form the outside dome profile required for a 202 beverage container.
As will be appreciated by one skilled in the art, an additional machine within the factory results in the requirement of an additional piece of expensive capital equipment, which must also be maintained at a significant yearly expense. Further, an additional piece of equipment occupies valuable floor space within the limited confined space of a manufacturing facility. Furthermore, typical reform equipment currently in use in a typical container manufacturing plant have inherent cost related to the wear of mechanisms and tooling, which can create performance issues if maintenance is not performed on a regular basis. It is highly desirable to reduce such maintenance, as performing the maintenance results in the machine being out of service for manufacturing use, and also requires personnel to service the machine and replacement parts, all of which add to the total cost of producing beverage containers.
One example of an attempt to solve the aforementioned problems is described in U.S. Pat. No. 5,934,127 to Ihle, (“the '127 patent”), which describes an apparatus for reforming the bottom portion of a container by utilizing a container rotating device to spin the container while reforming a bottom portion of the container. Unlike the invention described in the '127 patent, the present invention does not require the rotation of the container body, which is held in a static position while a reforming/reprofiling assembly rotates around the longitudinal axis of the container. This has numerous advantages, including a self-contained unit which needs no external cams, levers, or mechanisms to actuate the reprofiling tools or reforming tools. The unit is actuated by container movement into the tool, or tool movement into the container or both. The unit easily mounts to existing flanging/reforming/reprofiling/necking machines common in most container manufacturing facilities. Holding the container body in a static position is beneficial, as spinning containers are relatively difficult to convey out of a machine. Furthermore, the tooling of the present invention is easily set up and changed over from existing tooling for reforming and reprofiling containers, whereas the apparatus described in the '127 patent requires the purchase and installation of an entirely different machine.
Accordingly, a need exists for an apparatus and process which is capable of producing a metallic container which does not require a separate machine or separate process to both reform and reprofile an end portion of the container. Additionally, it would be beneficial to have a process which reduces overall maintenance in a manufacturing facility, and to reduce the inherent wear of machinery and the tooling associated therewith.